make spec file for rpmbuild

Readme.md

@@ -26,7 +26,14 @@ GOPATH=`pwd` GOOS=darwin GOARCH=amd64 go build telwho.go
 # Packaging
 __Prerequisite: before packaging the `telwho` binary need to be build for linux with one of the above mentioned command.__
 
-The RPM package for RHEL7 can be build via the docker build image as follows:
+The RPM package can be build as follows:
+```
+git clone https://git.psi.ch/gfa_rpms/gfa-telwho
+cd gfa-telwho
+rpmbuild -ba gfa-telwho.spec
+```
+
+Alternatively building it via the docker build image is also possible:
 
 ```bash
 docker run -it --rm -v $(pwd):/data paulscherrerinstitute/centos_build_rpm:7 package gfa-telwho.spec